Hours after the U.S.-led airstrikes began overnight, targeting Islamic State militants (also known as ISIS or ISIL), Syria's Ministry of Foreign Affairs released a statement claiming it had been given advance warning by the U.S. that the airstrikes would be launched.

The statement, broadcast on state TV, read: "Yesterday (Monday) the Foreign Minister, Walid Muallem, received a letter from his American counterpart John Kerry via the Iraqi foreign minister, in which he informed him that the United States would target the terrorist group ISIS in Syria."

Such a statement would be at odds with the U.S. Administration's insistence that it would not inform the Syrian government of any potential airstrikes targeting Islamic State militants inside Syria.

The U.S. is hesitant to do anything that would overtly signal collaboration with Syrian President Bashar al-Assad's regime. "Joining forces with Assad would essentially permanently alienate the Sunni population in both Syria and Iraq, who are necessary to dislodging ISIL," deputy National Security Adviser Benjamin J. Rhodes said last month.

The U.S.-led airstrikes targeted the defacto IS headquarters in the Syrian city of Raqqa, as well as bases, checkpoints and training centers of the militant Islamic ground in at least four Syrian provinces. Bahrain, Saudi Arabia, the United Arab Emirates, Jordan and Qatar joined the United States in the military operation, although it is unclear to what degree they were involved.